Posted on the OSN SuperSite March 26, 2008
Femtosecond laser-associated LASIK complications can occur but are manageable, surgeon says
ALICANTE, Spain — The introduction of femtosecond laser technology has greatly benefited LASIK, but femtosecond laser-related complications exist and can occur in some cases, according to a surgeon speaking here.
Fortunately, if managed appropriately, none of the potential intra- or postoperative complications would jeopardize surgical success, said J. Vicente Rodriguez, MD, at the Alicante Refractiva International meeting.
Dr. Rodriguez said that he uses an IntraLase femtosecond laser (Advanced Medical Optics) and thus focused on possible complications associated with this device. In particular, suction loss may occur during surgery when creating the raster pattern, he said.
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“You can continue with the treatment, using the same cone and a new ring. [But] if suction loss occurs when you are on the visual axis, it is better to wait about 1 month and then go about 40 µm deeper,” he said. “If suction loss occurs during the side cut, repeat the side cut only, reducing the flap diameter with a new, smaller ring.”
Vertical gas breakthrough represents another common complication and may occur when creating thin flaps of 100 µm or less or if there is a focal break or a scar in the Bowman’s layer, he said.
“If this happens, you should never try to lift the flap because you are likely to end up with a buttonhole,” Dr. Rodriguez said.
On the other hand, a horizontal gas breakthrough may occur when the gas is vented in quick bursts.
Another potential complication is opaque bubble layer (OBL), which is a collection of gas bubbles in the intralamellar space, above and below the resection plane. Early OBL tends to spread ahead of the raster pattern, while late OBL appears as opaque patches in areas of the raster pattern, he said.
“OBL is an excess of gas and water and may be due to several reasons. It is more common in brown eyes and may occur when energy power levels are too high or when the pocket is near the limbus, not deep enough or too narrow,” Dr. Rodriguez said.
OBL occurs in about 20% of patients and disappears after 15 minutes to 45 minutes. It does not affect surgical results, although it may create problems with using the eye tracker and when lifting the flap, he said.
Occasionally, gas bubbles can also diffuse into the anterior chamber via Schlemm’s canal.
Dr. Rodriguez noted that such a complication is not severe, but it can disrupt the excimer laser tracking system and may require several hours to fully dissipate.
Postoperative complications, namely diffuse lamellar keratitis (DLK) and transient light sensitivity syndrome (TLSS), were more common with the previous generations of IntraLase and are rarely reported with the latest 60 kHz model, he said.
“In femto-LASIK, [DLK] might be related to energy levels since the latest generation of IntraLase is associated with very few of these cases,” Dr. Rodriguez said.
TLSS is a rare phenomenon strictly related to femto-LASIK and generally appears 2 weeks to 6 weeks postoperatively. It might be caused by keratocyte activation or gas migration to the corneal periphery or to the episclera.
Patients can present with moderate to extreme light sensitivity, although they maintain good visual acuity. TLSS disappears spontaneously between 1 month and 3 months postop, and it can be treated with corticosteroids, Dr. Rodriguez said.
“Again, this problem seems to have been overcome by the latest generation of IntraLase,” he noted.
